1. Field of the Invention
The present invention relates to systems for carrying solid bodies entrained in a fluid stream, and has particular application to sludge treatment systems.
2. Description of the Prior Art
In waste water treatment systems it is common to pass the waste water through a settling or sedimentation process to permit solid materials to settle out of the water and form sludge, which consists of fine particulate solids in suspension. Since the sludge has a high water content, before the solid material therein can be effectively disposed of, substantially all of the water must be removed therefrom in a dewatering apparatus, such as a centrifuge or a filter press. In order for the dewatering apparatus to work most efficiently, the solid material must be in the form of solid particles or bodies of a particular size, which is typically substantially greater than the size of the particles as they come from the settling or sedimentation process.
Accordingly, the sludge is first conditioned by mixing it with a flocculent, such as a polyelectrolyte, which causes the solid particles to agglomerate or clump together to form what is known as "floc". The size of the floc clumps or bodies is a function of the mixing energy applied in the conditioning apparatus which mixes the sludge with the flocculent. Heretofore, system operators have determined whether or not the floc is of the proper size by simply visually observing it as it enters the dewatering apparatus. This has several drawbacks. First of all, in some applications it is necessary to view a moving stream of conditioned sludge which makes it difficult to accurately gauge the size of the floc. Furthermore, in some applications it is not possible to view the conditioned sludge as it enters the dewatering apparatus.
Also, the floc size is partly a function of turbulence which the conditioned sludge stream undergoes as it passes from the outlet of the sludge conditioning apparatus to the dewatering apparatus. Thus, it is a function of the piping system design, which may include a number of elbows, valves or the like which introduce substantial turbulence. Such turbulence can subject the floc to high shear forces which may break up the floc particles and thereby partially destroy the effect of the sludge conditioning process. Accordingly, what the viewer sees entering the dewatering apparatus may be quite different from what is produced by the sludge conditioning apparatus and if the floc entering the dewatering apparatus is unacceptable, it may be very difficult to determine whether the problem lies in the piping system design or in the amount of energy imparted in the sludge conditioning apparatus.